chore: update gen-fern-preview workflow to change directory before generating docs

Author: dslovinsky

.github/workflows/gen-fern-preview.yml

@@ -43,6 +43,7 @@ jobs:
         env:
           FERN_TOKEN: ${{ secrets.FERN_TOKEN }}
         run: |
+          cd docs-site && \
           OUTPUT=$(fern generate --docs --preview 2>&1) || true
           echo "$OUTPUT"
           URL=$(echo "$OUTPUT" | grep -oP 'Published docs to \K.*(?= \()')